Upper Mantle Amphiboles and Micas and TiO2, K2O, and P2O5 Abundances and 100 Mg/(Mg+Fe2+ Ratios of Common Basalts and Andesites: Implications for Modal Mantle Metasomatism and Undepleted Mantle Compositions

Kaersutite-Bearing Xenoliths and Megacrysts in Volcanic Rocks from the Funk Seamount in the Southwest Indian Ocean

“…In composition and occurrence the brown amphiboles match the high-Ti and K/Na, lowMg/Fe and Cr amphiboles that occur in group II xenoliths, as veins in xenoliths and as megacrysts (Wilkinson and le Maitre, 1987). Interstitial amphiboles in group I xenoliths have higher Mg/Fe and Cr, and much lower Ti (Wilkinson and le Maitre, 1987).…”

“…Interstitial amphiboles in group I xenoliths have higher Mg/Fe and Cr, and much lower Ti (Wilkinson and le Maitre, 1987). Megacryst and xenolith amphibole are very similar to megacrysts forming a tighter cluster, at somewhat higher Na contents.…”

Cr-rich magnesiokatophorite as an indicator of mantle metasomatism by hydrous Na-rich carbonatite

“…Amphibole analyses from the Ataq xenoliths have been reported by Varne (1970), Varne and Graham (1971), Menzies and Murthy (1980), and Chazot et al (1994Chazot et al ( , 1996aChazot et al ( , 1996b. They show compositions of chromian pargasite -edenite with intermediate Na 2 O/K 2 O = 2.5, which are similar to those in ordinary metasomatic amphiboles from mantle rocks (e.g., Francis, 1976;Dawson and Smith, 1982;Arai, 1986;Wilkinson and Le Maitre, 1987;O'Reilly and Griffin, 1988;Dawson, et al, 1988;Witt and Seck, 1989). Here, we report the petrographic and chemical characteristics of an unusual amphibole, magnesiokatophorite, and discuss its importance in mantle metasomatism.…”

“…Mantle metasomatism, which enriches depleted or undepleted mantle to produce new hydrous minerals and other minerals, is a well -documented phenomenon both in mantle xenoliths and in massif peridotites (e.g., Roden and Murthy, 1985;Wilkinson et al, 1987;O'Reilly and Griffin, 1988;Arai and Takahashi, 1989;Bodinier et al, 2004;Shaw et al, 2005). The formation of new, frequently hydrous minerals as a result of the metasomatic influx is termed modal (Harte, 1987) or patent (Dawson, 1984) mantle metasomatism.…”

Elemental and Sr-Nd-Pb isotopic compositions of late Cenozoic Abaga basalts, Inner Mongolia: Implications for petrogenesis and mantle process

“…These include the high Mg values (68~75) and Ni (>300 ppm) and Cr (>500 ppm) contents (Frey et al, 1978;Wilkinson and Le Maitre, 1987). However, the Mg values (57.9~66.3) of the Abaga basalts indicate that they might not represent primitive basalts, but probably have undergone a certain degree of fractional crystallization.…”